Artificial arm



July 25, 1950 s. M. MOTIS ETAL ARTIFICIAL ARM 3 SheetsSheet 1 FiledApril 6, 1948 JOS'EPH 0. CHHPMHN INVENTORS GILBERT M. M0776 QTTOBNEVJuly 25, 1950 cs. M. MQTIS ETAL ARTIFICIAL ARM 3 Sheets-Sheet 2 FiledApril 6, 1948 O O b m! ON 3\ hm HTTOB/VEV m m 7 m 0 H m MHV .CW p T 2HEP 6 mm Patented July 25, 1950 ARTIFICIAL ARM Gilbert M. Motis, Burbank,and Joseph 1). Chapman, Inglewood, Calif., assignors to NorthropAircraft, Inc., Hawthorne, Califi, a corporation of CaliforniaApplication April 6, 1948, Serial No. 19,375

9 Claims.

. I ,The present, invention relates to artificial arms, and its primaryobject isto provide an arm havinga wrist unit embodying passive, ormanually pre-set fiexion and extension of the wrist, together withautomatic supination of the wrist driven member responsive to fiexion ofthe forearm. More specifically, one of the objects of the invention isto provide a wrist unit having provision for both. fiexicn-extensicn andpronationsupination movements, and in which the pronation-supinationmovement takes place beyond, or .distally from the fiexion-extensionaxis. This is the ,exact reverse of the arrangement employed in allprior devices of like nature known to us, and results in certainadvantages which are impossible of attainment with the prior devices.

With the present invention, the wrist unit consists of a first memberwhich is pivoted on the forearm component for swinging movement aboutthe flexion-extension axis, and a second member which is journaled onthe first memher for rotation about the pronation-supination axis.Flexion and extension movements are passively, controlled; i. e., theaforesaid first member ofthe wrist unit is adjusted angularly withrespect to the forearm by using the other hand, or by pressing the sameagainst the body or some stationary object such as a table, chair, orthe like.- When the wrist has been adjusted to the desired degree offiexion, the unit is locked and remained in fixed angular relationshipto the forearm centerline until readjusted.

Pronation and supination movements of the wrist unit are coupled toforearm fiexion, and are accomplished by means of a force-transmittingsystem ,which connects the rotatable memberof the wrist to the upper armcomponent. This force-transmitting system is so constructed and arrangedthat when the forearm is flexed, the, rotatablemember of the wrist unitis automatically turned in a manner closely approximating the supinationof. the natural Wrist. Since the rotatable member of the wrist unit isjournaled on the swingable first member, fiexion of the latter causesthe supination axis tobe positioned at an angle to theforearmcenterline, and thehookor hand is thereafter caused to rotateabout the inclinedaxis. When the wrist unit is thus positioned with apredetermined amount of fiexion'the coordinated supination of the wristmember about the inclined axis as the forearm is flexed produces aleveling action at the hand or hook, en ablingan eating utensil to beheld level while 'itis being raised from ,the

table to the mouth. .This self-leveling action greatly facilitates ,theprocess of eating, as well as the performance of other acts such assmoking, shaving, and the like, wherein the hand is raised to the face.Such self-leveling action cannot be obtained in prior devices having thefiexion-extension axis located beyond the point at which supinationbegins, as this latter arrangement merely causes the flexed wrist andhand to be swung in an arcuate path about the fixed supination axis. I

Another important object of the invention is to provide an artificialarmwhaving-a rotatable wrist member coupled to. the upper arm component,whereby the wrist .is supinated when the forearm is flexed; together,with means for interrupting the drive to the wrist member andsimultaneously lockingthe latter againstrotation, so that the hook orhand-can be selectively locked in any angular, position about'thepronation-supination axis. V

Still a further object of the invention is to provide an arm of theclass described, wherein the force-transmitting control member whichoperates the associated hook or hand passes through and is confined to apointrepresenting the centerv about which all supination and fiexionmovements take place. By thus confining the path of the control memberto thefcommon center for both directions of movement of the wrist, theeffective, distance, between the ends of the control member is held.constant at all times, and operation of the hook or hand is notaffected by the position. of the same about either of its axes.

The foregoing and other objects and advantages'of the present inventionwill become apparent to those skilled in the art upon consideration ofthe following detailed, description of the preferred embodiment thereof,reference being had tothe accompanying drawings, wherein:

Figure 1 is a partially broken away perspective view of an extended armembodying .the principles of the presentinvention;

Figure 2 is a ,cut away side view of the same;

Figure 3 is a view similar to Figure 2, but with the forearm flexed, andthe, wrist unit turned on its pronation su'pination axis; I

Figure 4 isa sectional top plan view ,of the arm, as taken along theline '4-4 in,Figure 2;

Figures ,is a-slightly enlarged sectional view taken along the line 5.-5in Figure3;

Figure 6 is a fragmentary top plan view of the wrist unit and hook,showing-the same in three positions ,of fiexion;

Figure 7 is an enlarged sectional view taken along the line 'l'| inFigure 4, showing the wrist unit coupled to forearm flexion;

Figure 8 is a view similar to Figure 'l, but showing the wrist unitdisconnected from the upper arm component and locked against rotation;-l.

Figure 9 is an enlarged sectional view taken along the line 3-9 inFigure 4.

In the drawings, the reference muneral l designates the artificial armin its entirety, said arm comprising an upper arm component H, to whicha forearm component [2 is connected by an elbow joint l3. Mounted 'onthe outer end of the forearm member 12 is a wrist unit M, the distal endof which is formed with an attach plate l that is adapted to receives.hook unit "5. In the embodiment illustrated, the upper arm component I 1consists of a stump socket l3 which is preferably made up of laminatedplastic-impregnated'fabric, formed to receive the stump in asnug-fitting engagement. The lower end of the stump socket l9 ismoldedover and bonded'to an annular flange on a housing forming a part of theelbow joint unit 13. The elbowunit I3 is the same as that disclosed inthe copending application of Meyer Fishbein, et al., S. N. 747,690,filed May 13, 1947, to which reference may be had for details ofconstruction and operation. I 3 The-housing 201s generally cylindricalin shape, with a spherically curved outer end portion, and flats 2|formed on opposite sides thereof. A saddle 22 is mounted on the upperend of the forearm member I2, and has two laterally spaced ears '23which are disposed to lie against the flats 2|.

Extending through the housing 23 and journaled suitable bearings thereinis a hinge pin 24, the ends of 'which project from the flats 2i and arerigidly connected to the ears 23. Inside the housing 20 is a lockingdevice (notshown) for locking the forearm member in any one of a largenumber of closely spaced angular positions relative to the upper armcomponent H. i

v The saddle 22 is semi-cylindrical in shape, and embraces the bottomhalf of the housing 20. flange 25 project from the outer end of the sadedle 2'2; and bonded to the flange is :a forearm shell '26, preferably oflaminated plastic-impregnated fabric. An opening 21 is cut out of thetop portion of the shell 26 adjacent the elbow joint to provideclearance for the housing 20 when the forearm member is flexed, as shownin Figure 3. At its outer end, the forearmfshell126 fits over and isbonded to an annular flange 30 projecting rearwardly from the back of aring shaped memher 31. Projecting forwardly from the top and bottomedges of the rin 31 are tongues 32 and 33 which provide support for thewrist unit M.

The wrist unit [4 consists of a housing 34 which is pivoted on theforearm component [2 for angular movement about the fiexion-extensionaxis, and the attach plate 15 that is journaled on the housing 34 forrotation about the pronationsupination axis. For the purposes ofthepresent invention, the wrist-flexion-extension axis is considered tobe disposed at right, angles to the elbow hinge axis; while thepronation-supination axis extends generally forwardly from theflexion-extension axis and is perpendicular, thereto. When the'w'ristunit [4 is straightened out, the prone.- tion-supin ation axissubstantially coincides with the longitudinal centerline of the forearm"component I2, and when the wrist member 34; is swung around on theflexion-extension axis, the pronation-supination axis swings with it.Flexion 4 is the bending of the wrist to move the hand or hook towardthe body; while extension is the 0pposite movement, tending tostraighten the wrist, or move the hand away from the body. Pronation isthe turnin of the hand to a palm-down position; while supination is theturning of the hand to :a palm up position.

The hinge connection forming the fiexion-extension axis of the wristincludes two vertically spaced tongues 36, 31 which extend rearwardlyfrom the member 34 and overlap the tongues 32, 33, respectively. A pivotpin 40 is inserted into a hole in the top tongue 32 and is held thereinby a set screw 39, said pin being journaled in a bushing 4| in tongue36. In axial alignment with the pin 40 is another pivot pin 42 which isinserted into a hole in the bottom tongue 33 and is journ aled in abushing 43 in tongue 31. The pin 42 is held against turning by a setscrew 44 (Figure 9) that is threaded into a tapped hole in a boss 45formed on the inside surface of the tongue 33. Thewrist housing 34 isadapted to be-locked in any one of several angularly spaced positions offlexion, and to this end a bifurcated locking lever 46 is pivoted at 41on :a blade-like projection 50 extending upwardly from the top end ofpin 48. The lever 46 extends-longitudinally 0f the wrist housing 34, andits rear-end is pivotally connected at 5! to the head 52 of a pin 53which is disposedwithin a hole 54 in the tongue 36. The bottom endof-the pin 53 normally projects below the tongue 315 and is adapted toseat in an one of several holes 55 formed in the tongue 32,;said holesbeing arranged in :a circular arc about the axis of pin 40. In thepreferred embodiment illustrated, there are five of the holes 55, themiddle one of which gives a straight-out position for the wrist, and theothers giving positions of 22 and 45 degrees of flexion or extension toeither side of the straight-out position. A spring 56 bears upwardlyagainst the freeend of the locking lever 45, urging the same intolocking engagement.

The outer end of the cylindrical wrist housin 34is threaded internallyat fill to receive the threaded barrel 6l of an annular bearin sup portmember 62. Pressed intoa cylindrical seat 63 in the member 62 istheouter race '64 of ball bearings 65. The inner race 66 0f the ballbearings is mounted on the outer suriiace 'lfl'of an annular flange'llgprojecting rearwardly from the back of the attach plate l5 The innersurface of the flange H is threaded at 72 to receive a locking ring 13,the back end of which is provided with a radial flange 14 that engagesthe inner race 66 to clamp the latter inplace.

Projecting rearwardly from the'back side of the attach plate I5 throughthe center or'uie locking ring 13 is a tubular extension 15 having acentral bore 16 formed therein. The tubular extension 15 might be formedintegrally with the attach plate, as shown, or made as a separate partto facilitate manufacture. A sleeve bushing 30 is pressed into thebore'16, and slidably-dis-J 'posed'within the bushing is a cylindrie alcoupling member 8!, the outer end of which is formed with a socket '82that 'is adapted to r e ceijve a companionate couplingmember ontheliool; 16 so as to provide an operating connectioii there with.Thecoupling memberjal has pins]?! pro- Jctin re l 'l m e l i s d s t e fand ns t. gi s sl i ehg u v rtsndifie grogvs. 1 in F b h ng w om thQQUPl member against turning,

fflh hook it websi is .da i a iy mounted on'the-outer-faceof theattachplate It,

- outer face of the attach platelli. 1.;A-hook;control coupling member-;(not shown) projectsfrom the vback face of the .coupling-.plate.1l.4.andis :adapted .toseat in: the socket-.82. of the coupling :member. 8 Iv as. the coupling .p1ate.34-.approaches full zseating engagement withv-the::-attach:.=p1ate-..I 5.; .and :theci u said coupling members arethereafter connected togethertomovei 'as oner-c Thea-coupling member -onthe unit IIi:isoperativelyconnected to apiv- .oted. hook 86,-.and.causes =.the lattertto ;;be -closed against a stationary :hookvll. Iwhenzthelinterconz: 15

- nected coupling. members were movedaxially toward the right in thebore;-of-.-bushingz.80. l!l2he mechanism for actuating that pivoted:hookaBB forms no part of thepresent-invention, and therehereln; .s s, Acontrol wire90 ;is-;attached-.-1n anysuitable manner to the inside. ofthe coupling member 8| and extends rearwardly therefrom through thebushing 80 into the forearm shell n. The rearend of the wit-e90- is'trained over the top of a small pulley 9I formed-in.oneendofwahub:92which is journaledrfor rotation on..-a transversely disposed tubularsupport 93. The tube 93 is held at its ends by two insert members 94 and945-);30

which are embedded in the side walls of theshell 26. One end of'the tube93"has a splined; connection at 95 with the member 04?, thereby-lockingthe tube against rotation;

. Projecting radially *from the. hub- 92 alongsideadm the small pulley9| antarm having apin-'91 extending through .a. holein its-router end. Afitting I00 attached to'the end of control wire 90 .is engaged on oneprojecting endof the .pin 9.1,

to form an anchorage for thezwlrei The-Othemsm end of the pin-91'projectslaterally-from the opposite sideof the-arm Stand. is engagedby. one end of a spring IOI; the other end of the. spring being anchoredto a-screww I02 which extends through the shell 28 and flange-25 ofthe-saddle 22. The spring-IOI pullsnonrthearm 96, exerting acounterclockwisetorque onthehub. 92. s'sAt the outer end of the hub 92is-a-large -pu1ley. I-03, and trained around the -Iatter is: a control-cableizl04.

The cable I04 is attached tohthe pulley I03 and-s50 extends rearwardly.from the. top. part .thereof through the opening 21and.upwardly-alongthe upper arm component I I. The cable I04 ispreferably enclosed within-a spring-woundhousing (not shown) and isattached atritszupper end.to.;-, 55

the usual shoulder harness, whereby aipull can be applied to the .cablewhenetheoharnessed shoulder is shrugged downwardly-and forwardly.Automatic supinationv of the wrist member I 5 responsive to. forearmflexion iswobtained-bymo means of a force-transmittingesystem which willnow be described. "Pivotedcat I05 on opposite sides of the elbow housing.-.2.0.-:are-two side bars I06 which are connectedat their. front endsby a crossbar I01 to forma yoke I I0-.- The crossban m g I0'I extendsthroughand is slidable withina hole I II (see Figures 7 and 7.8)..formed in the outer end of a lever arm-I I2. -The leverarmJ I2 isjournalled intermediate. its-ends on the tubular support 93 andisslidable axially thereon; The-=b0t- 7 -is..disposede:generallymarallel months forearmmd- .=on.by means of set screws.1213.:1- j 1' at, mSlida-bly: mounted: on the tubular support? alongsidethe lever arm :II2 iscadownwardly exroller.

-centerline; and is SllPDOl'llEdi-fIiOIIlwUBiOWIbY azb'all bearingroller I I6, which is mounted on a pim:t

. securedin alinedholes in;the.-ends;of two bracket iiarms .:I2 I.t.-andI22. ;:.The bracket zarms -I2I,.;I22 are mounted. on and depend. from'thertubular support 93,.and are locked against turning there.-

tending stationary gear sector. :I.2 4'- -.having. .teeth 125 of thesame pitch and pitch diameter'as'the teethz-l I4. The gear sector I24.isadapted toxabe shifted axially along the. tubular; supportzz93,

carrying the lever arm I .I2 and rotatablegearsector-H3 with it, and tothis end a rod .-I2 6-is:slidably. disposed within the tubular.supportmem- .ber. The ends of the rod I 26 project a'short dis-:tance-beyond the'ends of the tubular member. 93 and have buttons I30provided thereon, whereby fore need notebe describedrzin*furtherixdetail go' the amputee cancs'hift the rod' in one; directionor the other by pressing on one of the buttons.

The stationary sector I 24. is connected to :the'rod IZB-bymeans of ascrew I3I whichisthreaded into both of the members I24 and I26, andextends through axially elongated slots I32 in opposite sides ofthe-tubular support member 93.

The lever arm' I I2 is confined on the opposite side by a ring I33which'lis: slidably mounted on .the tubular support [93. \The ring I33:.is connected to the rod .I26 by means of" a;.screw-I34 which isthreaded into both of the members I33 and I26, and extends throughaxially elongated slots 13%: in opposite sidesof. the tubular supportmember 93. Thus;= .whenthe rodrflIZG iis shifted axially within thesupport member 93,the

'ring a I33 -and stationary gear sector- 124: are moved with it, andsince the lever arm. II2-is confined between these members, the leverarm is also shifted axially withthe rod-- I26. Detent means are providedfor holding the rod I26 in -either of itstwo positions;said-detentmeansbeadapted to-seat ineither of two notches l40'or I M(see Figures 7 and: 8) in-the 1 inside surface of the tubular member 93.l

J The rack II5-is clamped between two sidebars 142 which extend downover the sides ofthe roller IIB, thereby centering the rack-on theDownwardly extending projections I43 and I44 at the front and rear endsofthe rack II5 are'engageable with theroller IIG to limit the fore andaft travel of the rack. v i v The side bars I42 extend forwardlyand'upwardly from the rack I I5 and aresecured at their front ends toopposite sides of another rack I45. The teeth of the rack I45 aredisposed along one side thereof, and mesh with a pinion I4Bthat isjournalled on the-pin 42. The rack I45 is confined on the other side bya ball bearing roller 1% which is mounted on a pin I5I extending downinto a hole in the boss 45 of tongue 33.

Fixedly mounted ontop of the pinion I46 isa bevel gear I52, theteethof'which mesh with another bevel gear I53-formed integrally withthe tubular portion I5 at the rear end thereof. Thus, the wrist memberI5 is rotated about the prone.- tion-supination axis by bevel gears I52and I53; the former being. coaxial with the flexion-extension axis, andthe/latter. beingcoaxialwith the pronation-supination; axis. .Since theaxesciof .the gears rzcoincidei withcrthe; axes of .rmoyement .or the..wrist;member...J 5.2.:2the :meslri. ofzthe'z'gears unaffected by the.position. of the wrist memher.

In. order to maintain the path of the control wire 90 at a substantiallyconstant length for-all angular positions of the wrist member I abouteither of its axes, the control wire is confined between two laterallyspaced rol1ers.i54 which .areiarranged on opposite sides of thepronationsupination axis and slightly to the. rear of-the"fiexion-extension axis. The rollers I54 are spaced .apart justslightly. more than the diameter of the wire 90, as shown in Figure 5,and thezplane of their axes is preferably located about .078 to the rearofthe flexion-extension axis. Thisarrangement has been found to give asubstantially constant length to the path of the control wire forallangular positions of the wrist housing 34 aboutthe flexion-extensionaxis, and since the path of the control wirev also lies. directly on'the pronation-supination .axis, the length of the :path of the controlwire is unaffected by rotation of the wrist. member I5on its ballbearings releasing the lock, which is done by pressing, downwardlyon'the free outer end of the locking lever 46 to unseat the pin 53 fromits hole 55. The wrist housing 34 is then swung around to the desiredposition of fiexion, and the looking lever 46 is released, allowing thepin 53 to seat in another hole 55. If the arm is to be used with wristsupination coupled to forearm flexion, the left hand button I30 on therod I26 is pressed inwardly, shifting the rod to the-right. Lever arm H2is carried to the right with the rod I26, engaging the sector II 3 withthe rack H5, and at the same time, the stationary gear sector I24 ismoved out of engagement with the rack H5. In this position, flexion ofthe forearm with respect to the upper arm causes the yoke IiIl to moveforwardly relative to the forearm component I2, rocking the lever arm H2and gear sector H3 in a counterclockwise direction. This rotationalmovement of the gear sector I I 3 causes the rack H5 to be movedrearwardly,carrying the rack I45 with it and thereby rotating the pinionI46, and bevel gears I52, I53, which drives the wrist member I 5 aboutits pronation-supination axis.

If it is desired touncouple the wrist unit I4 from the upper armcomponent, the, right hand button I 30 on the rod I25 is pressedinwardly, shifting the movable gear sector H3 out of mesh with the rackH5, and carrying the stationary gear sector I24 into engagementtherewith. With the rack I thus meshed with the stationary gear sectorI24, the wrist member I5 is locked against rotation, and remains in afixed position with respect tothe forearm component I2. One of theadvantages of the invention is that the angular position of the hookunit I6 about the pronation-supination axis can readily be adjusted bymerely flexing the forearm while the gear sector H3 is meshed with therack H5, un-

rod: L I26 is athen shifted to the left, locking the wrist member"35inthe adjusted position.

While we: haveshown and described in considerableodetail' whatwebelieveto bethe preierrediorm of our. invention, it is'to'beunderstood .that: such details are notrestrictive,- and that variouschanges may be-made in the shape and arrangement ofthe'. several partswithout departing from the scope of theinvention, as defined in theappended claims.

.-We claim i -1. In an-artificial arm having an-upper arm component. anda forearm component swingably connected thereto by an-elbow joint,awrist unit comprisingawmember pivoted on the outer end ofsaid-forearmcomponent for swinging movement aboutrthe wristfiexion-extension axis;

another memberjournaled on said first named member for rotation aboutthe pronationsupinationaxis, said last-named member being spacedoutwardly from and swingable about said 'fiexion-extension axis, anddrivingmeans connected to said upper arm component and having a portionthereof coaxial with said flexionextension axis for rotating saidlast-named member about said pronation-supination axis responsive toflexion and extension of .saida-forearm component with respect to said.upper arm component. 1 i

' 2. :In an artificial arm having a'forearm component, a wrist unitcomprising a member pivoted on said forearm fcomponent"v for angularmovement about the fiexion-extension axis, another member journaled. onsaid fir'st-named member a for rotation .a-boutrthe pronation-supinationaxis,

said pronation supination axis 'beingswingable a with said first-namedmember about said flexionextension. axis, said-last-named member havinga portion extending rearwardly through said 15 first-named membercoaxial. with said pronationsupination axis, and rotatable udrivinguneans 'zcoaxial with :said fiexioneextension axis and engageable :withsaid rearwardly extending portiontoerotate'said last-named member aboutsaid pronation-supination axis. I

53. In .an artificialarm'having a'forearm component, a wrist unitcomprising a'member pivoted extension -axis,- said :last-named memberhaving a tubular portion extending rearwardly through .said-first-n'amed. member .coaxial with said ,pronation-supinationaaxis, abevel gear fixedly mounted on saidxtuhular portion, and another bevelgear journaled on said forearm component coaxial withsaidwflexion-extension :axis and :meshing with said first-named bevelgear to rotate said last narne'd member about said pronationesupinationaxis.

L'In an artificial .arm having a forearm component, a wrist unitcomprising a member pivoted =on said "forearm component for angularmovement abou'ttheflexion-extension axis, another member journale'donsaid first-named member for rotation about a .pronation-supinationaxis intersecting said flexion-extension axis, the distal end 'ofsaid-*last-namedzmember being adapted 'to receive a hand or hook havingoperatingmechanism provided therein,- said last-named member having atubular portion-extending reartillthehook unit is :at. the desiredangle.The '(Q-AivartiIy through saidsfirst-named'member coaxial with saidpronation supination' axis, a 'flexible control cable extending" throughthe center of said tubular member and having means at the outer endthereof adapted for connection with said operating 'mechanism, a pair oflaterally spaced rollers disposed on opposite sides of said cableclosely adjacent said fiexio'n-extension axis, said rollers confiningthe-path of saidcable to the intersection of said axes, whereby thelength of said cable path remains constant for all angular positions ofsaid last-named member, and rotatable driving means coaxial with saidflexion-extension axis and engageablefwith, said tubular portion torotatesaid last-named'memher about said-pronation-supination axis. j

5. In an artificial arm' having an upperarm component and a forearmcomponent swingably connected thereto by an elbow joint, a wrist unitcomprising a member mounted on said forearm component for angularadjustment about the wrist fiexion-extension axis, another memberjournaled on said first-named member for rotation about thepronation-supination axis, said pronation-supination axis beingswingable with said first-named member about said fiexionextension axis,driving means connected to said upper arm component and to saidlast-named member for rotating the latter about saidpronation-supination axis responsive to flexion and extension of saidforearm component, and means for disconnecting said driving means andlocking said last-named member against rotation, whereby said last-namedmember can be locked in any angular position about saidpronationsupination axis.

6. In an artificial arm having an upper arm component and a forearmcomponent swingably connected thereto by an elbow joint, a wrist unitcomprising member mounted on said forearm component for angularadjustment about the wrist fiexion-extension axis, another memberjournaled on said first-named member for rotation about thepronation-supination axis, said pronation-supination axis beingswingable with said first-named member about said fiexionextension axis,a gear sector pivoted on said forearm component and slidable axiallythereon, a link connecting said sector to said upper arm component,whereby said sector is rocked when said forearm component is flexed andextended, a rack adapted to be meshed with said sector and to be movedlongitudinally thereby, said rack being connected with said last-namedwrist member to rotate the latter about said pronationsupination axis, anon-rotatable gear sector disposed coaxial with said first-named sectorand slidable axially therewith to engage said rack and hold the sameagainst longitudinal movement, and means for sliding said two gearsectors axially so as to disengage one of them from said rack and engagethe other one therewith, whereby said last-named wrist member may beoperatively connected to said upper arm component for supination coupledto forearm. flexion, or disconnected therefrom and locked againstrotation.

7. In an artificial arm having a forearm component and an upper armcomponent swingably connected thereto by an elbow joint, a wrist unitcomprising a member pivoted on said forearm component for angularmovement about the wrist flexion-extension axis, another memberjournaled on said first-named member for rotation about apronation-supination axis intersecting said fiexion-extension axis, thedistal end 10 j of said last-name'd'm'emberj being adapted tore- 'ceivea hand or hook having" operating mcha nism provided-therein, said "lastnamed member having tubular portion extending rearwardly through saidfirst-named member coaxial with said pronatio'ri supination axis,flexible control cable extent ling' through the center of saidtubular'fmember and having means at the outer end thereof adaptedfor'connectionwith said operating mechanism, a pair of laterally spacedrollers disposed on opposite side's'of said cable' closely adjacentsaid=fiexion extension axis, said rollers confining 'thepathof saidcable to the intersection of said axes, whereby thelength'of said cable"path remains constant" for all angular positions of said last namedmember, a bevel gear fixedly in'ou'ntedbn the rear end of said tubularportion, another bevel gear journaled on said forearm component coaxialwith said flexion-extension axis and meshing with said first-named bevelgear to rotate said last-named member about said pronation-supinationaxis, and means connected to said upper arm component for rotating saidlast-named bevel gear responsive to flexion and extension of saidforearm component.

8. In an artificial arm having a forearm component and an upper armcomponent swingably connected thereto by an elbow joint, a wrist unitcomprising a member pivoted on said forearm component for angularmovement about the wrist flexion-extension axis, another memberjournaled on said first-named member for rotation about apronation-supination axis intersecting said flexion-extension axis, thedistal end of said last-named member being adapted to receive a, hand orhook, said last-named member having a portion extending rearwardlythrough said first-named member coaxial with said pronation-supinationaxis, a bevel gear fixedly mounted on said rearwardly extending portion,another bevel gear journaled on said forearm component coaxial with saidflexion-extension axis and meshing with said first-named bevel gear,a'pinion fixed to said last-named bevel gear, a rack meshed with saidpinion, means connecting said rack with said upper arm component,whereby flexion and extension of said forearm component causes said rackto be moved longitudinally, thereby rotating said bevel gears andcausing said last-named wrist member to rotate about saidpronation-supination axis, and

means for disconnecting said rack from saidupper arm component andlocking the same against longitudinal movement, whereby said last-namedmember can be locked in any ngular position about saidpronation-supination axis.

9. In an artificial arm having a forearm component and an upper armcomponent swingably connected thereto by an elbow joint, a wrist unitcomprising a member pivoted on said forearm component for angularmovement about the wrist flexion-extension axis, another memberjournaled on said first-named member for rotation about apronation-supination axis intersec ing said flexion-extension axis, thedistal end of said last-named member being adapted to receive a hand orhook, said last-named member having a portion extending rearwardlythrough said first-named member coaxial with said pronationsupinationaxis, a bevel gear fixedly mounted on said rearwardly extending portion,another bevel gear journaled on said forearm component coaxial with saidflexion-extension axis and meshing with said first-named bevel gear, apinion fixed to i said lastena b v s as, 3-1 39 meshed with said pinion,a gear sector pivoted on said component and. slidable axially into andout of mesh with saidLrack, a link connecting said sector to said upperarm component, whereby said sector is rocked when vvsaid forearmcomponent is flexed and extended a non-rotatable gear sector disposedcoaxial with said firstnamed sector and: slidable axially therewith toengage said rack and hold the same against longitudinal movement; andneans for simultaneously sliding said two gear-seotorsiaxially so as todisengage one of them from .saidrack and engage the other one therewith,whereby said last-named wrist member maybe operatively connected to saidupper arm component for supination coupled to forearm flexion, or.disconnected therefrom REFERENCES men The following references areofrecord in the flle o! this'patentr I a UNITED STAT S PATENTS NumberName Date ,7

999,484 Carries I --I Aug. 1, 1911 1,046,966 Carnes III I -Dec. 10, 19121,507,682 Pecorella etal, Sept. 9, 1924 2,287,781

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